I understand Windows XP runs out next April and there will not any security patches from the Microsoft then on. If I install Xp in VIRTUALBOX as a guest to Ubuntu 13.04, will that be safe? Actually I have that kind of configuration at the moment and do not wish to discard XP. Please advise!
Thank you.

It largely depends on what you're using XP for, years ago I kept a Windows install for a single program, it didn't need to go on the net, the input files for it were grabbed on my Linux box and put on a shared partition; for that particular case I could now keep a pristine XP VM, blow it away after every use and restore the pristine container every time.

That's much the same as my situation. The only reason I keep an XP machine at all is to build the Windows versions of programs I develop. I do all the development on a Linux machine, then periodically I transfer the source to the XP machine to build that version. At the moment it has access to the internet, but it doesn't need it.

That's the first time I've seen a TinyURL that's longer than the address to which it points

Anyway, ReactOS is an impressive project given that (AFAIK) nobody is paid to work on it full-time. It can run various older Windows apps, but it's still very much in Alpha stage and not recommended for full-time use.

If you absolutely need to run one or two Windows apps, it's worth a try, and cheaper than a full Windows license.